Ahead of a big summer of sport, the BBC has begun low latency streaming trials on its iPlayer platform.
In what it said is the first step in trialling low latency streaming to the public, BBC Research and Development hopes to gain greater understanding into low latency’s performance in real-world conditions over viewers’ internet connections.
At present, viewers watching content streamed over the internet experience delays over those watching via traditional broadcast. The delay on iPlayer is currently around 40 seconds, although the BBC said it is not the same for all viewers. By contrast, broadcast services have an end-to-end delay of just 8-10 seconds. For live sports and events with a social media following, the impact can detract from the viewing experience.
This summer the BBC will be broadcasting a number of live sports events, including the UEFA Women’s Euros and Wimbledon.
Working with the teams responsible for the TV iPlayer product, BBC R&D has arranged for some viewers of BBC Two who have opted into the platform’s ‘beta’ mode to see an experimental low-latency stream using Low Latency DASH with chunked CMAF segments. Performance data from these sessions will provide quality and reliability comparisons with traditional live streaming from a variety of households with varying internet connections. If the trial proves successful, work will continue to fine-tune the stream and test different variants in an aim to maximise reliability, said the corporation.
Users who experience rebuffering will receive a slightly speeded up stream after a stall, which aims to maintain low latency while ensuring none of the action is missed. This requires functionality that is not currently available on all TVs and the trial will therefore only take place using devices that support variable speed playback capability. Later on, the trial may be extended across more devices.
The first phase of the trial is starting with a small number of devices but targeting those that have a significant number of viewers watching live streams. Initially, these are the third generation Amazon FireTV Stick, 2nd generation Amazon FireTV Stick 4K, and Samsung CU8000 and CU8500 TVs with more planned as the test continues. The trial will run between 9am and 5pm with enabled devices which have their location set to England or Scotland. Users experiencing problems can return to the conventional version by turning off ‘iPlayer beta’ mode.
The BBC said that “more work is needed to build a fully resilient, fault-tolerant system that can scale to the size of audience that the BBC serves for major sporting events,” adding that since common ways to ensure resilience themselves add delay, achieving it for low-latency streams is a challenge.
